Field of the Invention
The present invention relates to an image processing device and an image processing method.
Description of the Related Art
Broadly there are two kinds of nonuniformities in captured images. Specifically, these are illumination-based nonuniformities that occur because an illuminant is irradiated unevenly on an object at a time of capturing, and visnetting-based nonuniformities due to lens properties wherein it gets darker as you go from the central portion towards peripheral portions the captured image. Since an illumination-based nonuniformity occurs when capturing is performed a plurality of times when the size of the object is larger than the angle of view at the time of capturing a single shot, illumination-based nonuniformities tend to be larger in the longitudinal direction in particular. Also, a visnetting-based nonuniformity occurs in every captured image.
A shading correction technique is a known technique for correcting nonuniformities that occur in a captured image. In a technique disclosed in Japanese Patent Laid-Open No. 2007-81580, for example, a color chart and an illumination-based nonuniformity correction chart are captured under the same illumination, and correction of the foregoing two types of nonuniformities is performed based on the captured values for both charts. Also, in the technique disclosed in Japanese Patent Laid-Open No. 2011-124954, flash image capturing and image capturing under observation light are performed, correction data for performing shading correction is generated based on a correspondence relationship between pixel values of an image that is flash image captured and pixel values captured under an observation light source, and then the correction is performed.